Generally when ifup uses an interface which uses DHCP and which updates DNS, /etc/resolv.conf gets updated. /sbin/pump has an option -d which makes sure /etc/resolv.conf isn't updated every time. This should be an option in ifcfg-* so I don't have to edit ifup manually.
This can also be controlled by editing your /etc/pump.conf file, but it might be a good idea to add that as an option in the init script (by overloading PEERDNS?) since I'm not sure how you do this in dhcpcd's configuration files.
Well, -R is the dhcpcd equivalent to -d in pump. And /etc/pump.conf isn't created by default, so it wouldn't really be obvious.. it would make a lot more sense to put it in a variable in ifcfg.. Basically this is what my lines 94 & 95 look like in /etc/sysconfig/network-scripts/ifup: PUMPARGS="-d -h ${DHCP_HOSTNAME}" DHCPCDARGS="-R -h ${DHCP_HOSTNAME}" (As opposed to without -d & -R)
Sounds like a plan. Added in initscripts-5.53-1; just add PEERDNS=no to /etc/sysconfig/network-scripts/ifcfg-eth*.